<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" 
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg width="100%" height="100%" version="1.1"
xmlns="http://www.w3.org/2000/svg">

<rect x="20" y="20" width="250" height="250" style="fill:blue">
<animate attributeType="CSS" attributeName="opacity" 
from="1" to="0" dur="5s" repeatCount="indefinite" />
</rect>

</svg>